The present invention relates to improvements in starters, particularly to improvements in a shift lever for driving a pinion gear of a starter.
In a starter disclosed in, for example, Japanese Patent Laid-Open No. 5-180131 and No. 50-65806, a shift lever for driving a pinion gear by an electromagnetic switch is constructed with a resilient drive spring.
The drive spring may comprise two-layered leaf springs supported inclinedly at a middle portion thereof and having contact portions at both ends thereof. However, when the drive spring is operated, loss of kinetic energy by friction is caused because the respective leaf springs slide relative to each other. Therefore, kinetic energy necessary for driving the drive spring is requested to be larger by an amount of the loss by friction and load of an electromagnetic switch is increased by that amount. As a result, the size of the electromagnetic switch is large and heavy, thus consuming larger power.
Further, when a pinion gear is meshed with a ring gear of an engine, return force is exerted to the pinion gear by operation of a helical spline. Therefore, friction heat is generated at an end portion of the shift lever receiving the return force (for example, a portion in contact with a one-way clutch). As a result, there occurs permanent set in fatigue (reduction of resiliency) in the leaf spring by influence of the friction heat.
Moreover, the shift lever has no set load before being brought into contact with a movable cylindrical body including the pinion gear. Since the movable cylindrical body is not kicked impulsively, performance of bringing the pinion gear in mesh with the ring gear becomes insufficient. In the case of the pinion gear and the ring gear fail to mesh each other sufficiently, frictional wear occurs therebetween and the durability becomes insufficient.